5G Overall System Trial— An application of 5G Ultra-Low-Latency Communication
to Truck Platooning —Hitoshi Yoshino

Advanced Technology
Research Department
SoftBank Corporation

Ryo Yamaguchi

Advanced Technology
Research Department
SoftBank Corporation

1. Introduction

Manabu Mikami

Advanced Technology
Research Department
SoftBank Corporation

Research and development is under way toward thecommercialization of 5th generation mobile communication
systems (5G) in 2020. In addition to extending the capabilities of
4G networks with enhanced Mobile Broadband (eMBB), 5G will
provide capabilities in the new domains of Ultra Reliable and Low
Latency Communication (URLLC) and massive Machine TypeCommunication (m-MTC), and is highly anticipated as social
infrastructure for our advanced information society. URLLC andm-MTC in particular have potential for developing new markets,and establishing concrete 5G applications for these is an urgentmatter.
The Ministry of Internal Affairs and Communications (MIC)
began 5G system trials in Japan in FY2017[1]. These trials request
evaluation of 5G wireless system technologies for commercial use,
as well as trials of 5G in collaboration with other vertical sectors,
meaning use of 5G in sectors other than mobile communications.
The trials discussed here belong to the 5G URLLC test
group (Group V, or GV) led by SoftBank, and deal with a use
case applying 5G to truck platooning. This article reports on these
activities in GV.

technology and maintains a safe separation between vehicles
according to their cruising speed. ACC has been implemented
and many vehicles are already equipped with it. However, whencontrolling based only on the measured distance between vehicles,
there is a significant delay between when the lead truck begins
to slow down and when the following distance changes. There isfurther delay until the following truck begins to slow down. For
this reason, if only ACC is used, a longer following distance must
be maintained to prevent collisions.
On the other hand, Cooperative ACC (CACC) controls
speed based on speed and acceleration information sent from thelead truck to the following truck by inter-vehicle communication,
which can greatly improve control of the following distance when
the lead truck needs to brake suddenly. This also enables stable
operation with less fluctuation in following distance (huntingoscillation) due to control delay. Fuel consumption can be further
reduced and traffic capacity of roads increased while maintaining
safety by further reducing the following distance and increasing
the number of platooned trucks, so using 5G URLLC, which
realizes low latency and high reliability, in this field is very
promising.

2. Application of 5G to truck platooning

3. Trial description

Truck platooning involves multiple trucks driving together
in a convoy. The truck platoon is controlled as a unit by using
inter-vehicle communication. Development to implement truck
platooning is currently underway in several countries around theworld.
Several social issues can be resolved through use of truck
platooning. Platooning can enable trucks to drive closer together
to reduce wind resistance, which can reduce fuel consumption
and reduce CO2 emissions. It has been shown that a platoon of
three trucks travelling 4 m apart at 80 km/h consume 15% lessfuel[2]. If the distance between trucks is reduced to 2 m, the fuelconsumption would be reduced by 25%. Reducing the distance
between vehicles can also increase the traffic capacity of roads,
mitigating congestion. This could further reduce CO2 emissions.
In Japan, an aging driver population and driver overwork are alsosocial issues, so truck platooning can reduce the burden on drivers
and increase safety.
Adaptive Cruise Control (ACC) measures the distance
between a lead vehicle and following vehicle using radar or otherIn the GV trials, the ultra-low latency radio capabilities
of 5G were used in the transport field for two use cases: (1)Communication between vehicles involved in platooning, and(2) Remote monitoring and operation of the entire truck platoon.
These use cases are shown in Figures 1 and 2.
There are two main communication requirements for theseuse cases. The first is low-volume, low-latency communicationneeded for the vehicle control systems (speed, acceleration,vehicle positions, etc.). The other is high-volume, low latency
communication needed for the video monitoring system, tomonitor the whole platoon (monitoring the truck surroundings,etc.). The former must also be highly reliable.
Figure 3 shows the forms of communication for platooning,including (1) Vehicle-to-Network-to-Vehicle communication(V2N2V), (2) direct vehicle-to-vehicle communication (V2V
Direct, Sidelink), and (3) vehicle-to-network communication(V2N). Communication with (1) above is between vehicles
through a base station, and can provide relatively stable and lowlatency communication with the help of the base station. WithNew Breeze Autumn 201815

■ Figure 1: Use case 1: Inter-vehicle communication for truck platooning(Vehicle control and video monitoring around following truck)■ Figure 2: Use case 2: Remote monitoring, remote operation(Communication
between platooned trucks and remote operation control center)(2), there is a possibility that signals become blocked by other
4.7 GHz band was used in the tests, and the evaluation was done
vehicles coming between the platooned trucks, so it could becomein a test environment with vehicle-to-vehicle communication via
less reliable than (1), but it can achieve lower latency than (1).
base station. The tests were done assuming truck speeds up to 90
With (3), delays within the network dominate vehicle-to-network
km/h. An example of over-the-air latency measurement is shown
communication, but it is needed for remote monitoring andin Figure 5. It shows that at a speed of 87 km/h, the transmission
operation of the vehicles.
delay on the air was 0.58 ms.
In FY2017, application of 5G communication to self-drivingof following trucks in a platoon is being studied, so the basic(2) Throughput characteristics
performance of communication necessary for vehicle control andWhile platoon driving, the surroundings of the following vevideo monitoring of the surroundings of following truck was
hicles must be monitored at the lead truck for safety. The feasibilevaluated. Specifically, the communication types (1) and (2) above
ity of low-latency, high-volume communication for video monitorwere tested. The specifications of test equipment are■ Table 1: Test equipment specifications
shown in Table 1.

4. Trial results
A truck platoon driving environment using large
trucks was set up on the Tsukuba City test course toevaluate 5G communications equipment (Figure 4).
(1) Latency characteristics
The latency characteristics of 5G communicationequipment were measured in tests, with consideration
for use in vehicle control for platoon driving. The16

New Breeze Autumn 2018

■ Figure 3: F orms of communication for platooning■ Figure 4: Real truck platooning test

■ Figure 5: V 2N low latency communication performance
assuming vehicle remote monitoring andcontrol (4.7 GHz band)■ Figure 6: Throughput characteristics (28 GHz band)ing was tested. The test environment involved vehicle-to-vehicle
direct communication with vehicles separated by approximately
10 m. The 28 GHz band was used to ensure wide bandwidth.
Figure 6 shows the relationship between distance traveled andthroughput. The figure shows that throughput of approximately 2
Gbps was achieved. This shows that video transmission is possible
without increasing the delay due to video encoding, thanks to suchhigh throughput.

5. Conclusion
We conducted basic performance evaluations applying 5G totruck platooning on a real test course. We studied two cases ofcommunication: low-volume, low-latency communication needed
for platooning (for truck control), and high-volume, low-latency
communication (for monitoring the following vehicles). The
test results confirmed that the communication requirements foradvanced truck platooning were met.
In the future, we will conduct integration testing for aplatooning control system as well as testing to ensure reliability.
References[1] Ministry of Internal Affairs and Communications, “5G System Trial Begin,” Press Release,
http://www.soumu.go.jp/menu_news/s-news/01kiban14_02000297.html, May 2017.
[2] K. Aoki, “Current Activities of Development on the Automated Truck Platoon,” pp.303-309,
IPSJ Journal, Vol.54 No.4, Apr. 2013.

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